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From: Florian Weimer <fw@deneb.enyo.de>
To: JeanHeyd Meneide <phdofthehouse@gmail.com>
Cc: musl@lists.openwall.com
Subject: Re: [ Guidance ] Potential New Routines; Requesting Help
Date: Wed, 25 Dec 2019 21:07:05 +0100	[thread overview]
Message-ID: <87zhfg185y.fsf@mid.deneb.enyo.de> (raw)
In-Reply-To: <CANHA4Oie9gY0munzvHDXdEq8486FvO4BCjM9s_QYpVQga2wNww@mail.gmail.com> (JeanHeyd Meneide's message of "Tue, 24 Dec 2019 18:06:50 -0500")

* JeanHeyd Meneide:

>      I hope this e-mail finds you doing well this Holiday Season! I am
> interested in developing a few fast routines for text encoding for
> musl after the positive reception of a paper for the C Standard
> related to fast conversion routines:
>
>      https://thephd.github.io/vendor/future_cxx/papers/source/C%20-%20Efficient%20Character%20Conversions.html

I'm somewhat concerned that the C multibyte functions are too broken
to be useful.  There is a at least one widely implemented character
set (Big5 as specified for HTML5) which does not fit the model implied
by the standard.  Big5 does not have shift states, but a C
implementation using UTF-32 for wchar_t has to pretend it has because
correct conversion from Unicode to Big5 needs lookahead and cannot be
performed one character at a time.

This would at least affect the proposed c8rtomb function.

I posted a brief review of the problematic charsets in glibc here:

  <https://sourceware.org/ml/libc-alpha/2019-05/msg00079.html>


  reply	other threads:[~2019-12-25 20:07 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-24 23:06 JeanHeyd Meneide
2019-12-25 20:07 ` Florian Weimer [this message]
2019-12-26  2:13   ` Rich Felker
2019-12-26  5:43     ` JeanHeyd Meneide
2019-12-30 17:28       ` Rich Felker
2019-12-30 18:53         ` JeanHeyd Meneide
2019-12-26  9:43     ` Florian Weimer
2019-12-30 17:31 ` Rich Felker
2019-12-30 18:39   ` JeanHeyd Meneide
2019-12-30 19:57     ` Rich Felker
2019-12-31  3:58       ` JeanHeyd Meneide

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